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x86/apic: Construct a selector for the interrupt delivery mode 

There are quite some switches which are used to determine the final
interrupt delivery mode, as shown below:

1) Kconfig: CONFIG_X86_64; CONFIG_X86_LOCAL_APIC; CONFIG_x86_IO_APIC
2) Command line options: disable_apic; skip_ioapic_setup
3) CPU Capability: boot_cpu_has(X86_FEATURE_APIC)
4) MP table: smp_found_config
5) ACPI: acpi_lapic; acpi_ioapic; nr_ioapic

These switches are disordered and scattered and there are also some
dependencies between them. These make the code difficult to maintain and
read.

Construct a selector to unify them into a single function, then, Use this
selector to get an interrupt delivery mode directly.

Signed-off-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: yinghai@kernel.org
Cc: bhe@redhat.com
Link: https://lkml.kernel.org/r/1505293975-26005-2-git-send-email-douly.fnst@cn.fujitsu.com
This commit is contained in:
Dou Liyang 2017-09-13 17:12:44 +08:00 committed by Thomas Gleixner
parent e19b205be4
commit 0114a8e877
1 changed files with 52 additions and 0 deletions
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52
arch/x86/kernel/apic/apic.c
View File

@ -1218,6 +1218,58 @@ void __init sync_Arb_IDs(void)
APIC_INT_LEVELTRIG | APIC_DM_INIT);
}
enum apic_intr_mode {
APIC_PIC,
APIC_VIRTUAL_WIRE,
APIC_SYMMETRIC_IO,
};
static int __init apic_intr_mode_select(void)
{
/* Check kernel option */
if (disable_apic) {
pr_info("APIC disabled via kernel command line\n");
return APIC_PIC;
}
/* Check BIOS */
#ifdef CONFIG_X86_64
/* On 64-bit, the APIC must be integrated, Check local APIC only */
if (!boot_cpu_has(X86_FEATURE_APIC)) {
disable_apic = 1;
pr_info("APIC disabled by BIOS\n");
return APIC_PIC;
}
#else
/* On 32-bit, the APIC may be integrated APIC or 82489DX */
/* Neither 82489DX nor integrated APIC ? */
if (!boot_cpu_has(X86_FEATURE_APIC) && !smp_found_config) {
disable_apic = 1;
return APIC_PIC;
}
/* If the BIOS pretends there is an integrated APIC ? */
if (!boot_cpu_has(X86_FEATURE_APIC) &&
APIC_INTEGRATED(boot_cpu_apic_version)) {
disable_apic = 1;
pr_err(FW_BUG "Local APIC %d not detected, force emulation\n",
boot_cpu_physical_apicid);
return APIC_PIC;
}
#endif
/* Check MP table or ACPI MADT configuration */
if (!smp_found_config) {
disable_ioapic_support();
if (!acpi_lapic)
pr_info("APIC: ACPI MADT or MP tables are not detected\n");
return APIC_VIRTUAL_WIRE;
}
return APIC_SYMMETRIC_IO;
}
/*
* An initial setup of the virtual wire mode.
*/